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[193.205.81.5]) by smtp.gmail.com with ESMTPSA id l127-v6sm4856902wma.41.2018.07.20.08.36.06 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 20 Jul 2018 08:36:07 -0700 (PDT) Subject: Re: [PATCH V3] sched/deadline: Update rq_clock of later_rq when pushing a task To: Juri Lelli , Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Clark Williams , Luca Abeni , Tommaso Cucinotta , Steven Rostedt , Ingo Molnar , stable@vger.kernel.org References: <20180720124615.GM2476@hirez.programming.kicks-ass.net> <20180720124821.GB2512@hirez.programming.kicks-ass.net> <20180720125329.GD3642@localhost.localdomain> From: Daniel Bristot de Oliveira Message-ID: <183815b1-50dd-9027-31df-a18a604719e8@redhat.com> Date: Fri, 20 Jul 2018 17:36:06 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180720125329.GD3642@localhost.localdomain> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/20/2018 02:53 PM, Juri Lelli wrote: > On 20/07/18 14:48, Peter Zijlstra wrote: >> On Fri, Jul 20, 2018 at 02:46:15PM +0200, Peter Zijlstra wrote: >>> On Fri, Jul 20, 2018 at 11:16:30AM +0200, Daniel Bristot de Oliveira wrote: >>>> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c >>>> index fbfc3f1d368a..8b50eea4b607 100644 >>>> --- a/kernel/sched/deadline.c >>>> +++ b/kernel/sched/deadline.c >>>> @@ -2090,8 +2090,14 @@ static int push_dl_task(struct rq *rq) >>>> sub_rq_bw(&next_task->dl, &rq->dl); >>>> set_task_cpu(next_task, later_rq->cpu); >>>> add_rq_bw(&next_task->dl, &later_rq->dl); >>>> + >>>> + /* >>>> + * Update the later_rq clock here, because the clock is used >>>> + * by the cpufreq_update_util() inside __add_running_bw(). >>>> + */ >>>> + update_rq_clock(later_rq); >>>> add_running_bw(&next_task->dl, &later_rq->dl); >>>> - activate_task(later_rq, next_task, 0); >>>> + activate_task(later_rq, next_task, ENQUEUE_NOCLOCK); >>>> ret = 1; >>>> >>>> resched_curr(later_rq); >>> >>> Why isn't push_rt_task() affected by the very same issue? >> >> Aah, I see, its the add_running_bw() think; for which RT doesn't have a >> counter-part. > > Right, but doesn't enqueue_top_rt_rq end-up being called by activate_ > task on lowest_rq? Mmm. AFAICS we have: push_rt_task() { activate_task() { enqueue_task(,,(flags=0)) { if (!(flags & ENQUEUE_NOCLOCK)) update_rq_clock(rq); enqueue_task_rt() { enqueue_rt_entity() { enqueue_top_rt_rq(); } } } } So we will have the clock updated already... Am I missing something? Thanks, -- Daniel